The Beaufort scale is a standardized scale used to measure and describe wind speeds based on observable effects on the sea and land. It was developed in 1805 by Francis Beaufort of the British Royal Navy. The scale ranges from 0 to 12, where 0 represents calm conditions with no wind and sea like a mirror, and 12 represents hurricane-force winds with devastated conditions and very high waves. Each level corresponds to a range of wind speeds, wave heights, sea state, and visible effects on land such as movement of trees and difficulty walking. The scale is primarily observational rather than relying on precise measurements. An extended scale with levels 13 to 17 exists for very intense tropical cyclones but is rarely used internationally. The Beaufort scale remains widely used for marine and weather forecasting purposes to communicate wind strength concisely.
Here is a brief summary of key wind force levels on the Beaufort scale:
- 0: Calm (<1 knot), mirror-like sea, smoke rises vertically
- 3: Gentle breeze (7-10 knots), large wavelets with some whitecaps, leaves in constant motion
- 6: Strong breeze (22-27 knots), large waves forming with foam and spray, large branches in motion
- 9: Strong gale (41-47 knots), high waves with dense foam, slight structural damage possible
- 12: Hurricane (≥64 knots), air full of foam and spray, sea completely white, devastation on land
The scale translates subjective visual observations into standard wind speed categories useful for navigation, meteorology, and safety.
